Portable bulk material containers are used in the oilfield for delivery and storage of proppant for hydraulic fracturing operations. The containers can be initially moved to the well site by transport and then moved around the well site with forklifts and are ultimately placed on a discharge actuation apparatus which routes the contents of the container to the fracturing blender where the proppant is mixed into the fracturing fluid. During fracturing operations many containers of proppant may be required, and the time between container exchanges can be as short 2 to 2.5 minutes. These bulk containers often have a sliding gate located at the bottom of a funnel chute through which the bulk material is discharged from the container. During each re-fill cycle, care is taken to make sure that the sliding gate is closed sufficiently to prevent any bulk material from inadvertently being discharged from the container during transport. In such containers, a gate pin is located below and centered on the gate, and is used by bulk receivers to open and close the gate. To prevent the gate from inadvertently opening during transport, the gate assembly often includes a keeper that hinges down when the container is in transport and captures the gate pin by way of a slot formed in the keeper that limits the travel of the pin, and thus the gate, to ensure that the gate does not open during transport.